Re: Optimize RAID0 for max IOPS?

[Wolfgang Denk <wd@denx.de>]

Dear =?ISO-8859-15?Q?Stefan_/*St0fF*/_H=FCbner?=,

In message <4D361F26.3060507@stud.tu-ilmenau.de> you wrote:
> 
> [in German:] Schätzelein, Dein Problem sind die Platten, nicht der
> Controller.

Irrtum.

> [in English:] Dude, the disks are your bottleneck.

Wrong.  Testing the same workload with soft RAID versus the h/w RAID
solution gives a _significant_ performance difference.

I happen to know which benchmarks 3ware (and other RAID controller
manufacturers) are optimizing their firmware for - IOPS is not even
mentioned there.

> On a 4-disk RAID0 software RAID can only outspeed this 3ware Controller
> with a really really fast processor.  The limiting factor is the disk's
> access time.  If SSDs are too expensive, then your actual performance is
> the max you'll get (maybe to replace the HWRAID controller might give a
> little speed-up, but not very much).

From some tests done before I expect to see a speed increase of >10.

Hey, even a single disk is performing better under this work load.

And fast processor? Yes, I have it, but what for? It spends most of
it's time (>90%, usually more) in iowait.

Best regards,

Wolfgang Denk

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